saving the animation
It's not clear what you did and what you are trying to achieve, so here is my best try:

If you want to render single image, you can press F12 (Top menu:Render>Render image). Then your image is displayed in Blender Render window. You can save this image by pressing Shift+S (Top menu: Image>Save as). Then you can choose filename and file type.

If you want to render image sequence, you have to go to output panel (usually located at bottom right of the screen (or right panel if you are using Rendering layout), its card has printer icon). Choose resolution, directory which should contain resulting files and file type (for example PNG). Then hit Ctrl+F12 (Top menu:Render>Render Animation). Images should appear in directory you choose, no other action is required.

If you want to render video file, you can do it similarly to prevous steps, but instead of choosing image type such as PNG, choose FFmpeg video and specify details in Encoding section. Again, after pressing Ctrl+F12, resulting file will show up in directory you have choosen in Output card.

If you render bigger project, it's good idea to render to images in case something breaks during render, or you realize you want to change something and re-render some images. If you want to make single video from image sequence, open new Blender file using File>New>Video Editing. Hover mouse over Video Sequencer and press Shift+A. Click Image/Sequence. Go to directory where you stored your image sequence, select all images (A) and press Add Image Strip. Choose render-resolution and frame-rate and render in a same way as I described above.

Pressing Ctrl+S (File>Save) or Shift+Ctrl+S (File>Save as) is reserved only for saving .blend file.